1. Field of the Invention
The present invention relates to a 4-cycle engine including an oil tank mounted to one side of an engine body, and an oil slinger accommodated in the oil tank and adapted to scatter an oil stored in the oil tank to generate a lubricating oil mist.
2. Description of the Related Art
Such 4-cycle engine is already known, as disclosed in, for example, Japanese Patent Application Laid-open No.9-170417.
In the known 4-cycle engine, an oil tank is formed integrally on the one side of the engine body, as disclosed in the above publication.
In this conventional 4-cycle engine, however, there is a problem that the oil stored in the oil tank is liable to be overheated by heat emitted by the engine body.
Therefore, it is considered to amount the oil tank at a location spaced apart from the engine body so that the heat is difficult to be transmitted from the engine body to the oil tank. However, this brings about an increase in size of the engine, which is not preferred.
Accordingly, it is an object of the present invention to provide a 4-cycle engine of the above-described type, wherein the oil tank can be disposed at a location spaced apart from the engine body without bringing about an increase in size of the engine, to thereby suppress the transmission of the heat from the engine body to the oil to the utmost.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a 4-cycle engine comprising an oil tank mounted to one side of an engine body, and an oil slinger accommodated in the oil tank and adapted to scatter an oil stored in the oil tank to generate a lubricating oil mist, wherein the 4-cycle engine includes a timing transmitting case interposed between the engine body and the oil tank, and a timing transmitting device accommodated in the timing transmitting case for interconnecting a crankshaft and a camshaft which are supported in the engine body.
With the above first feature, the heat transmission from the engine body to the oil tank can be shielded by the timing transmitting case, thereby preventing overheating of the oil stored in the oil tank. Moreover, the timing transmitting case is essential for a OHC-type engine and hence, never bring about an increase in size of the engine.
According to a second aspect and feature of the present invention, in addition to the first feature, a case cover is coupled to the timing transmitting case to cover an outer surface of the transmitting timing device, and the oil tank is connected to the case cover to share a sidewall with the case cover.
With the second feature, the case cover and the oil tank can be formed integrally with each other, thereby simplifying the structure to contribute, to thereby contribute to a reduction in cost.
According to a third aspect and feature of the present invention, in addition to the first or second feature, a bowl-shaped portion is formed on an outer wall of the oil tank with its center aligned with the crankshaft so that the bowl-shaped portion is recessed into the tank, and the oil slinger is formed to extend along a curved convex surface of the bowl-shaped portion.
With the third feature, a dead space in the oil tank can be reduced by forming the bowl-shaped portion on the outer wall of the oil tank. Moreover, even in a laid-sideways position of the engine with its bowl-shaped portion facing downwards, the oil present around the bowl-shaped portion can be stirred and scattered efficiently by the oil slinger. Therefore, generation of the oil mist by the oil slinger can be conducted effectively, while providing a decrease in ineffective amount of oil stored in the oil tank.
According to a fourth aspect and feature of the present invention, in addition to the third feature, a recoiled starter is disposed outside and adjacent to the oil tank, and a member driven by the recoiled starter is secured within the bowl-shaped portion to an outer end of the crankshaft extending through the bow-shaped portion.
With the fourth feature, a space in the bowl-shaped portion can be utilized effectively for disposition of the driven member, and the recoiled starter can be disposed in the vicinity of the oil tank to thereby contribute to compactness of the entire engine.
According to a fifth aspect and feature of the present invention, in addition to the first feature, a heat-shielding air guide plate is disposed between the engine body and a carburetor connected to the engine body for shielding a heat and guiding cooling air from a cooling fan provided on the crankshaft, the heat-shielding air guide plate being integrally connected to the timing transmitting case, whereby the timing transmitting case and the heat-shielding air guide plate are constituted as a single united part.
With the fifth feature, the heat-shielding air guide plate is formed integrally with the timing transmitting case secured to the engine body to constitute the single united part. Therefore, the heat-shielding air guide plate is supported by the timing transmitting case, whereby a bolt or bolts for securing the heat-shielding air guide plate to the engine body can be omitted, or the number of bolts used can be reduced greatly. Thus, it is possible to reduce the number of parts and the number of assembling steps by virtue of the integral formation of the timing transmitting case and the heat-shielding air guide plate, to thereby contribute to a reduction in cost.
According to a sixth aspect and feature of the present invention, in addition to the fifth feature, an oil-feed conduit and an oil-return conduit are formed on the timing transmitting case in order to transfer the oil mist between the oil tank and portions to be lubricated within the engine body.
With the sixth feature, it is possible to reduce the number of parts and the number of assembling steps by integral formation of the timing transmitting case and the oil-feed conduit as well as the oil-return conduit, thereby greatly contributing to a reduction in cost.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.